Transparent Vacuum Sapphire Optical Windows Polished Flanges Glass

Sapphire glass is an application of synthetic sapphire generally produced by subjecting aluminum oxide powder under extreme heat and pressure. Further heat treatment removes internal stresses before processing into thin sheets. The resulting output is a transparent material that is more durable than standard glass. Take note that a synthetic sapphire has the same physical properties as naturally-occurring sapphire.

ADVANTAGES OF SAPPHIRE GLASS

Accu-Glass Products' Sapphire vacuum viewport flanges are rated for both high and ultrahigh (UHV) vacuum applications.

The use of high purity sapphire and low expansion alloys allow these viewports to be repeatedly baked out at temperatures up to 350°C. Sapphire in these viewports is a synthetic, hexagonal single crystal anisotropic material which displays substantially different physical, thermal, dielectric and optical qualities when measured along different axes. Crystal orientation of Accu-Glass Products' viewports is normal to the optical axis or 90° orientation.

UV grade sapphire has a transmission range of 0.250µm to 4.50µm while regular sapphire has a transmission range of 0.30µm to 4.00µm. Poor surface finish can contribute as much as 10% to overall transmission losses. All viewports are supplied with flat faces which have been finished to a 50-20 scratch-DIG. Thermal gradients should not exceed 20°C per minute.

HOW DOES IT WORK?

Glass sapphire windows allow the window to be mounted as close to the chamber as reasonably possible and allow the clearest access from the window surface on the air side. These windows are silver-brazed to Kovar® sleeves. They are mounted in stainless steel tube-weld adapters and CF type flanges for use below 1x10-11, or ISO type Kwik-Flange®. Optional flange weldments are available as special order.

Sapphire Window surfaces which are extremely hard and scratch resistant offer a minimum of distortion and provide maximum light transmission suitable for most applications. UV grade viewports have a 90° crystal orientation normal to the optical axis.

Features:

• Offers greater distortion-free view area
• ¾” and 1” are UV grade.
• Magnetic Kovar® content only 1% to 3%
• >80% Transmission from 250nm (UV Grade) to 4000nm
• CF and Weld mount bakeable to 450°C, 25°C/Min gradient
• Kwik-Flange® bakeable to 200°C

We can offer "Sapphire Viewports" available in series of standard sizes from 3/4 inch through 2 inch with a variety of flange options. Dimensions are in inches unless otherwise noted.

CAUTION: Although sapphire has a reasonable thermal conductivity, for safety, we strongly recommend that no viewport is exposed to a temperature ramp of greater than 2-3°C per minute, and that no viewport be exposed to direct thermal radiation. To limit thermal gradients when heating viewports, we recommend the viewing area and the flange be covered with many layers of aluminum foil to act as a reflective shield.